Posted: Sun Mar 25, 2018 0:46 Post subject: TP-Link TL-WR940N(US) Ver.6.0 available for analysis
I've got a brand new TP-Link router, with the model number and version in the subject line, that won't currently accept DD-WRT as most earlier versions will. (I tried several files that were offered, but all they did was brick the router until I managed to debrick it using an awkward TFTP recovery technique.) It is going to be popular, because outlets such as Fry's and Micro Center are selling it at bargain prices and it provides the fastest 802.11n that is available on 2.4 GHz. I would gladly crack the case and send pictures, list the chips, and/or send the router to someone who is willing to analyze it and get this model and version working with DD-WRT. Any takers?
Already did. As mentioned above, no DD-WRT firmware images which have been offered for this version of the router have worked, which is why I've posted this new topic and offered to supply hardware, photos, etc.
You will most likely have to TFTP the firmware. TP-Link Routers have TFTP client looking for a specific filename served by a TFTP server (your computer) at 192.168.0.66. I would suggest using TFTP32/TFTP64. You can determine the filename the router is looking for by examining the TFTP32/TFTP64 log.
Tried all three of the files in that archive. They did not work. GUI would not accept them, and when I got them into the router using TFTP (the file name requested from my TFTP server was wr940nv6_tp_recovery.bin) the router would never fully boot. It simply reset itself repeatedly. More analysis must be needed, which is why I am offering hardware, photos, etc. As for hooking up a serial cable: I have plenty of level converter chips around. Just need to know where on the circuit board to hook up. Might need to tack solder some wires if there is no header. Do not know whether native firmware produces any useful messages, or if any of those DD-WRT images will before the system crashes and reboots.
Here are photos of the board and the chips on it; they should be detailed enough for you to make out the numbers. I do not know if the stock firmware will send out any useful messages on its serial port. But if it seems as if this would be useful I believe I have an Exar SP3232EH or two floating around the workshop.
P.S. - If you compare these photos to the ones at https://wiki.openwrt.org/toh/tp-link/tl-wr940n (on the OpenWRT site), you'll see that the board layout is similar to that of V4.0, but with substantial cost reductions. (Among other things, there's only ONE LED in the whole unit, which serves as the WAN LED! There are none for the LAN ports or Wi-Fi.) The OpenWRT page suggests that the serial port will not work unless one creates solder bridges on the board and perhaps adds a pullup to the RX line.
Last edited by Brett Glass on Thu Mar 29, 2018 3:13; edited 1 time in total
Maybe a peek at their conversation and/or their code will help! The good news is that they seem to have made only minor tweaks to their v4 code and images. The changes mostly seem to involve the LED(s) - perhaps the v4 code toggles a PIO line that crashes the v6 - but also include a new signature for the binary.
Any chance that one of the developers could compile a DD-WRT image based on the information in my previous posting? The router is sitting and gathering dust until I can replace the TP-Link firmware, which is famously insecure.
ETA: This is going to be important, because Micro Center, Fry's, Best Buy, Newegg, and Amazon have sold out the older versions of the TL-WR940 and are now selling this one exclusively. If the developers don't start posting files that can be loaded onto this version, newly bought routers of this model will no longer be able to run DD-WRT.